"hidden" property ui option

[romancow]

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There could be a case to add a "hidden" ui option, such as her with the extra "male" object select:

Though considering there are cases we would want to be able to enable/disable empty object like this, how would this ui option be determined when webgme-taxonomy json schema is being created?

Also, it may not be necessary in this case since this property probably should be set to required, and then we can just hide required empty objects (since it has to be in the data and there are no settings for it). So then the question are there other cases for a "hidden" ui option? If it's not an empty object, it would seem necessary to show it to select the value(s), else what's the point of it being there?